Multi-Choice! A gold pendulum swings with angular acceleration a, and a point on the edge has tangential acceleration a. A silver pendulum swings with angular acceleration 3a, and a point on the edge has tangential acceleration 5a. How does the radius of the gold pendulum r gold compare with the silver pendulum r silver ?

A 1/15
B 5/3
C 15
D 3/5​​

An insulated thermos contains 148 g of water at 72.7 ˚c. you put in a 11.7 g ice cube at 0.00 ˚c to form a system of ice + original water. the specific heat of liquid water is 4190 j/kg•k; and the heat of fusion of water is 333 kj/kg. what is the net entropy change of the system from then until the system reaches the final (equilibrium) temperature?